Rate of heat flow
the rate at which heat flows between two systems
for example, if there are two systems with the same mass and specific heat and one, say System A, has an average kinetic energy (a temperature) of 500 K and system B has an average kinetic energy of 400 K and they are put in contact and after 30 seconds they both reach 450 K, the average rate of heat flow was (specific heat and masses = 1) 50J/30s, or rather 1.6J/s